SALMON have returned to a North Yorkshire river - for the first time in living memory.

Cod Beck, near Thirsk, has been presumed unfit for the species because of the acidic nature of the Swale, into which it flows.

However, anglers taking part in a fishing match at the beck spotted a dead salmon, which has now been examined by experts at the Environment Agency.

They discovered that the fish, a female, had lived in fresh water for two years, spent the winter in the sea, and had then returned to fresh water to spawn. Unable to find a mate, the fish perished before it could lay its eggs.

Fisheries scientist Paul Frear said: "This is a clear indication that the river water quality in the area is reaching levels not experienced for many years.

"It is a shame the fish was unable to spawn, but at least we have been able to gather plenty of information about it.

"Last summer, we also found a couple of young salmon while carrying out surveys on the Swale.

"This shows that at least some salmon are finding their way up river and successfully spawning."

The agency believes the acidic quality has been reduced during the past few months because of the wet weather.

This has allowed more fresh water than usual to flow through the river system towards the North Sea, giving salmon a better chance of swimming upstream.

Improved water quality in industrial areas by the Humber and Ouse, through which the salmon would have to swim, has also played a part.

The angler who found the salmon, Peter Wilkins from Knayton, near Thirsk, said: "At the time I thought it was unusual to see salmon in the water, so I went back to retrieve it, even though it appeared to be dead.

"It's wonderful to think that, with cleaner waters, we could be seeing salmon returning to this area of North Yorkshire on a regular basis."

Mr Fear said: "We'd be very interested in hearing from any other people who have spotted salmon in the Swale system."